KR101033723B1 - Developing roller, electrophotographic process cartridge, and electrophotographic apparatus for image formation - Google Patents

Abstract

Provided is a developing roller having a surface with sufficient flexibility which is excellent in suppression of penetration of a low molecular weight substance from an elastic material and excellent in toner releasability and hardly causes cracking even by repeated image formation. The developing roller is a roller for supporting and conveying the toner and developing the electrostatic latent image of the photosensitive drum with toner, and has an axial core, an elastic layer and a surface layer in this order. The surface layer includes a silicon oxide film containing a carbon atom chemically bonded to a silicon atom. The silicon oxide film preferably has an abundance ratio (O / Si) of oxygen atoms forming a chemical bond with a silicon atom to a silicon atom of 0.65 or more and 1.95 or less and a silicon atom of a carbon atom forming a chemical bond with a silicon atom (C / Si) of not less than 0.05 and not more than 1.65.

Toner, electrostatic latent image, axial core, elastic layer, surface layer, developing roller, tensile modulus, electrophotographic process cartridge, electrophotographic image forming apparatus

Description

TECHNICAL FIELD [0001] The present invention relates to a development roller, an electrophotographic process cartridge, and an electrophotographic image forming apparatus,

The present invention relates to a developing roller used in an electrophotographic image forming apparatus such as a copying machine or a laser printer, an electrophotographic process cartridge having the developing roller, and an electrophotographic image forming apparatus.

A contact developing system for developing an electrostatic latent image on a photosensitive drum by toner is proposed in which development is performed by bringing a developing roller having an elastic layer into contact with a photosensitive drum.

The developing roller used for contact development contacts the contact member while conveying the toner. Therefore, when the surface tension of the developing roller is strong, the conveyed toner may remain attached on the developing roller. The toner adhering to the surface of the developing roller as described above is gradually deteriorated by repeated contact between the developing roller and the photosensitive drum thereafter and finally fused on the surface of the developing roller to cause filming .

As a countermeasure against film formation of such a toner, Japanese Patent Application Laid-Open No. 09-62086 (Patent Document 1) discloses a technique in which inorganic particles having a property of releasing the toner are sprinkled on the surface of the elastic layer, A developing roller having an elastic layer with good chargeability and suppressing film formation is proposed.

However, according to the investigations of the present inventors, since the above-mentioned inorganic particles are adhered to the surface, they are easily separated during use, and it is difficult to maintain the film-inhibiting effect for a long period of time.

Further, in the case of a developing roller provided with an elastic layer, the image quality and the life of the photosensitive drum may be influenced.

It is necessary to suppress the adhesion of the low molecular weight substance exuding from the elastic layer to the photosensitive drum. However, in the developing roller according to the invention disclosed in Patent Document 1, it is difficult to satisfactorily prevent the adhesion of the low molecular weight substance to the photosensitive drum Respectively.

As a countermeasure against filming of conventional toners, a developing roller of the type in which at least one kind of resin is coated on the surface of the elastic layer is exemplified in the detailed description of the invention disclosed in Patent Document 1. Such a developing roller has a problem in reliability due to insufficient flexibility of the coating layer or adhesion to an elastic body.

Therefore, the present inventors have found that, from the viewpoint of further stabilizing the electrophotographic image with respect to the contact phenomenon,

1. It is possible to effectively inhibit permeation of low molecular weight components from the elastic layer,

2. It has a surface with excellent toner releasability, and

3. It has been recognized that development of a developing roller having a surface layer, which has sufficient flexibility and is hard to cause cracking even by repeated image formation, is important.

SUMMARY OF THE INVENTION Accordingly, it is an object of the present invention to provide a developing roller having a surface layer satisfying the requirements 1 to 3 above.

Means for Solving the Problems The inventors of the present invention have found that it is necessary to specify the material for forming the surface layer in order to solve the above problems and have finally reached the present invention.

That is, the developing roller according to the present invention is a developing roller for carrying and carrying toner and developing the electrostatic latent image of the photosensitive drum with toner, and has an axis core, an elastic layer and a surface layer in this order, (O / Si) of oxygen atoms forming a chemical bond with silicon atoms to silicon atoms is 0.65 or more and 1.95 or less, And the abundance ratio (C / Si) of the carbon atoms forming the chemical bond with the silicon atom to silicon atoms is not less than 0.05 and not more than 1.65.

Further, an electrophotographic process cartridge according to the present invention is an electrophotographic process cartridge detachably mounted on an electrophotographic image forming apparatus main body, and the assembled developing roller is the above developing roller.

Further, an electrophotographic image forming apparatus according to the present invention is an electrophotographic image forming apparatus having a photosensitive drum and a developing roller disposed in contact with the photosensitive drum, wherein the developing roller is the developing roller described above.

According to the developing roller of the present invention, permeation of low molecular weight substances from the elastic layer can be effectively suppressed. That is, even when the electrophotographic photosensitive member is contacted with the electrophotographic photosensitive member for a long time, adhesion of the low molecular weight substance permeating from the elastic layer to the surface of the electrophotographic photosensitive member can be effectively inhibited. As a result, a high-quality electrophotographic image can be stably obtained. Further, according to the developing roller of the present invention, the occurrence of filming on the surface of the developing roller is suppressed, and a stable image can be formed. Further, according to the developing roller of the present invention, peeling of the surface layer due to use can be effectively suppressed. Therefore, it is possible to further improve the durability of the developing roller.

1 is a cross-sectional view of an example of a developing roller.

Fig. 2 is an explanatory view showing a method of collecting a test piece for measuring a tensile modulus of elasticity. Fig.

3 is a schematic view of a SiOx film production apparatus by plasma CVD.

4 is an explanatory view showing a method of measuring the current value of the developing roller;

5 is a schematic diagram showing an example of a developing apparatus equipped with the developing roller of the present invention.

6 is a schematic diagram showing a process cartridge on which the developing roller of the present invention is mounted.

BEST MODE FOR CARRYING OUT THE INVENTION [

1 is a cross-sectional view of an example of a developing roller of the present invention.

The developing roller 1 of the present invention usually has an axial core 11 formed of a conductive material such as metal and has at least one elastic layer 12 on the outer circumferential surface thereof and at least one layer The surface layer 13 of the second electrode layer is laminated.

(Axial body 11)

The shaft body 11 has a cylindrical shape in the figure, but the shaft body may have a hollow cylindrical shape.

The developing roller 1 is generally used by applying or grounding an electrical bias. Therefore, it is preferable that the shaft body 11 is a supporting member and at least the surface is conductive as the conductive material. Therefore, the shaft body 11 is made of a conductive material which is sufficient to apply a predetermined voltage to the elastic layer 12, at least the outer circumferential surface of which is formed thereon. Specific examples of the structure of the shaft body include the following.

A shaft body made of metal or alloy such as Al, Cu alloy, SUS;

An iron shaft body on which a surface of Cr or Ni is plated;

ㆍ Shaft made of synthetic resin made by plating Cr or Ni on the surface.

In the developing roller used in the electrophotographic image forming apparatus, it is appropriate that the axis core body 11 generally has an outer diameter in the range of 4 mm to 10 mm.

(The elastic layer 12)

The elastic layer 12 is a molded body using rubber or resin as a raw material main component. Various rubbers conventionally used in developing rollers can be used as the raw material main component rubber. Specifically, the following can be mentioned. (EPDM), acrylonitrile-butadiene rubber (NBR), chloroprene rubber (CR), natural rubber (NR), isoprene rubber (IR), styrene-butadiene rubber (SBR) Rubber, epichlorohydrin rubber, hydride of NBR, polysulfide rubber, urethane rubber.

The resin mainly constituting the raw material is mainly a thermoplastic resin, and the following may be mentioned. Polyethylene resins such as low density polyethylene (LDPE), high density polyethylene (HDPE), linear low density polyethylene (LLDPE) and ethylene-vinyl acetate copolymer resin (EVA); Polypropylene type resin; Polycarbonate resins; Polystyrene type resin; ABS resin; Polyimide; Polyester resins such as polyethylene terephthalate and polybutylene terephthalate; Fluorine resin; Polyamide 6 such as polyamide 6, polyamide 66, and MXD6.

These rubbers and resins may be used alone or in combination of two or more.

Further, in the developing roller of the present invention, it is possible to use various components such as a conductive agent and a non-conductive filler, which are required for the function required for the elastic layer itself, and various additive components used for forming rubber and resin molded articles, Such as an accelerator, can be appropriately compounded in the rubber material of the main component.

As the conductive agent, either an ionic conductive material by an ion conductive mechanism or a conductive agent by an electron conductive mechanism may be used, or a combination thereof may be used.

Examples of the conductive agent by the electron conductive mechanism include the following. Metal powders and fibers such as aluminum, palladium, iron, copper and silver; Metal oxides such as titanium oxide, tin oxide, and zinc oxide; Metal compound powders such as copper sulfide, zinc sulfide and the like; The surface of suitable particles may be treated with electrolytic treatment, spray coating, mixed shaking, etc. with tin oxide, antimony oxide, indium oxide, molybdenum oxide, zinc, aluminum, gold, silver, copper, chromium, cobalt, iron, lead, Powder attached by the same; Carbon black-based conductive agents such as acetylene black, Ketjenblack (trade name), PAN-based carbon black, pitch-based carbon black, and carbon nanotube.

As the conductive agent by the ion conductive mechanism, the following may be mentioned. Alkali metal salts such as LiCF ₃ SO ₃ , NaClO ₄ , LiClO ₄ , LiAsF ₆ , LiBF ₄ , NaSCN, KSCN, NaCl; Ammonium salts such as NH ₄ Cl, NH ₄ SO ₄ and NH ₄ NO ₃ ; _{Ca (ClO 4) 2, Ba} (ClO 4) alkaline earth metal salts such as _2; Complexes of these salts with polyhydric alcohols such as 1,4-butanediol, ethylene glycol, polyethylene glycol, propylene glycol and polypropylene glycol and derivatives thereof; Complexes of these salts with monools such as ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, polyethylene glycol monomethyl ether and polyethylene glycol monoethyl ether; Cationic surfactants such as quaternary ammonium salts; Anionic surfactants such as aliphatic sulfonic acid salts, alkyl sulfuric acid ester salts and alkyl phosphoric acid ester salts; Amphoteric surfactants such as betaine.

These conductive agents may be used alone or in combination of two or more.

In addition, as a means for imparting conductivity to the elastic layer, a method of adding a conductive polymer compound together with a conductive agent or a conductive polymer may also be used.

The conductive polymer compound is a polymer compound made of a host polymer having a conjugated system such as polyacetylene and doped with a dopant such as I ₂ to conduct the conductive polymer.

Examples of the host polymer include the following. Poly (p-phenylenesulfide), poly (p-phenylenylene), poly (p-phenylene vinylene), poly (Dimethylphenylene oxide), poly (bisphenol A carbonate), polyvinylcarbazole, polydiacetylene, poly (N-methyl-4-vinylpyridine), polyaniline, polyquinoline and poly (phenylene ether sulfone).

As the dopant, in addition to I ₂ , the following can be mentioned. Cl ₂ , Br ₂ , ICl, ICl ₃ , IBr, IF ₃ ; Lewis acids such as PF ₅ , AsF ₅ , SbF ₅ , FeCl ₃ , AlCl ₃ and CuCl ₂ ; Alkali metals such as Li, Na, Rb and Cs; Alkaline earth metals such as Be, Mg, Ca, Sc and Ba, aromatic sulfonic acids such as paratoluenesulfonic acid, benzenesulfonic acid, anthraquinone sulfonic acid, naphthalene sulfonic acid, naphthalene disulfonic acid and naphthalene trisulfonic acid or alkali metal salts thereof.

Of these, carbon black-based conductive agents are suitable because they are relatively inexpensive and readily available, and can impart good conductivity regardless of the kind of rubber and resin material of the main component. As the means for dispersing the conductive agent in the form of a fine powder in the main component rubber and the resin material, the following conventional means may be appropriately used depending on the rubber and the resin material of the main component. Examples include roll kneaders, Banbury mixers, ball mills, sand grinders, and paint shakers.

Examples of the filler and the extender include the following. Silica, quartz powder, diatomaceous earth, zinc oxide, basic magnesium carbonate, activated calcium carbonate, magnesium silicate, aluminum silicate, titanium dioxide, talc, mica powder, aluminum sulfate, calcium sulfate, barium sulphate, glass fiber, organic reinforcing agent, organic filler.

These fillers may be subjected to hydrophobic treatment by treating the surface with an organosilicon compound.

As the antioxidant, known ones which are used for a polymer compound such as a hindered phenol antioxidant, a phenol antioxidant, a phosphorus antioxidant, an amine antioxidant and a sulfur antioxidant can be appropriately selected and used.

As the processing aid, known materials can be used. Specifically, fatty acids such as stearic acid and oleic acid, and metal salts and esters of fatty acids can be used.

For example, in order to produce a rubber molded article from a silicone rubber, a liquid silicone rubber is used as a subject, a polyorganohydrogen siloxane is used as a crosslinking component, and a crosslinking of rubber components is attempted using a platinum-based catalyst .

The thickness of the elastic layer is preferably 0.5 mm or more, and more preferably 1.0 mm or more in order to ensure the nip width in contact with the photosensitive drum and further satisfy the suitability for setting. The upper limit of the thickness of the elastic layer is not particularly limited as long as it does not impair the accuracy of the outer diameter of the developing roller to be manufactured. In practice, the thickness of the elastic layer is preferably 6.0 mm or less, particularly 5.0 mm or less. The thickness of the elastic layer is appropriately determined in accordance with its hardness in order to achieve a desired nip width.

In the present invention, the forming of the elastic layer can be performed by an extrusion molding method, an injection molding method or the like known in the art, but is not particularly limited. The layer constitution is not limited as long as it has the features described in the present invention, and it may be constituted by two or more layers.

The elastic modulus of the elastic layer having the surface layer is not particularly limited, but is preferably 1.0 MPa or more and 100.0 MPa or less, more preferably 1.0 MPa or more and 30.0 MPa or less. By setting the tensile elastic modulus of the elastic layer having the surface layer within the above-described numerical range, it is difficult for permanent stress to be generated in the contact portion of the developing roller to occur even when the developing roller is left in contact with a contact member such as an electrophotographic photosensitive member for a long period of time. Further, the pressure applied to the toner passing between the contact member and the developing roller is not excessively increased, and it is possible to effectively suppress the release or burial of the external additive of the toner and the penetration of wax or the like in the toner.

The tensile modulus in the present invention is measured according to the method described in JIS-K7113: 1995. In the present invention, as shown in Fig. 2, a sample having a length of 100 mm and a roller bearing capacity is cut out from the developing roller 1 to obtain a test piece 40 for measuring the tensile elastic modulus.

For the measurement, a universal tensile tester " Tensilon RTC-1250A " (trade name, manufactured by Orientech Kabushiki Kaisha) is used. In addition, the measurement environment is set at a temperature of 20 ° C and a humidity of 60% RH. In addition, the measurement is performed by setting each end portion of the test piece 10 mm on the chuck, and measuring the chuck length 80 mm and measuring speed 20 mm / min. The obtained average value of the tensile modulus of 5 samples is calculated and used as the tensile elastic modulus of the elastic layer having the surface layer of the developing roller.

(Surface layer 13)

The developing roller of the present invention has a surface layer 13 covering the surface of the elastic layer 12, as shown in Fig. The surface layer includes a film of a silicon oxide film (hereinafter also referred to as " SiOx film ") containing carbon atoms chemically bonded to silicon atoms. That is, the SiOx film included in the surface layer 13 has chemical bonds of Si-O and Si-C. (O / Si) of oxygen atoms chemically bonded to silicon atoms with respect to silicon atoms is 0.65 or more and 1.95 or less. Also, the abundance ratio (C / Si) of the carbon atoms forming the chemical bond with the silicon atom to the silicon atom is 0.05 or more and 1.65 or less.

It is more preferable that the abundance ratio O / Si is 1.30 or more and 1.80 or less. When the abundance ratio O / Si is less than 0.65, it is difficult to prevent contaminants from bleeding from the elastic layer, so that contamination of the photosensitive drum in contact with the photosensitive drum may become a problem when used as a developing roller. On the other hand, when it is more than 1.95, the SiOx film itself is hard and easily cracked, and when used as a developing roller, streaks tend to occur in the obtained image due to cracks.

In addition, the abundance ratio C / Si is more preferably 0.10 or more and 0.70 or less. If the abundance ratio C / Si is less than 0.05, the adhesion between the silicon oxide film and the surface of the elastic layer decreases, and it may become difficult to obtain a uniform and appropriate surface layer. On the other hand, when the abundance ratio C / Si is more than 1.65, the surface of the film tends to become tacky (tacky), and when used as a developing roller, releasability to the toner decreases and filming tends to occur.

The existence ratio of each element in the surface layer is obtained as follows.

The surface of the surface layer 13 of the developing roller was treated with a 2p orbit of Si, 1s of O and C (a product of < RTI ID = The peak due to the binding energy of the orbit is measured. The abundance ratios of the respective atoms are calculated from each peak, and O / Si and C / Si are obtained from the abundance ratio obtained.

The chemical bonding of SiOx was carried out by a Fourier transform infrared spectroscopy (FT-IR) apparatus "SpectrumOne" (trade name, manufactured by Perkin Elmer Japan Co., Ltd.) Of the test results. That is, by the presence of Si-O oscillation peak (450cm ^-1), Si-C stretching peak (800 to 820cm ^-1), to confirm the presence of the chemical bond of Si-O and Si-C. Further, since the deviation in the position of the O / Si and C / Si values of the surface layer according to the present invention formed by the method described later can hardly occur, the measurement point may be located at one point in the surface layer.

As a method for forming a film of SiOx according to the present invention on the elastic layer, the following methods can be mentioned. Wet coating methods such as dip coating, spray coating, roll coating and ring coating; Physical vapor deposition (PVD) methods such as vacuum deposition, sputtering, and ion plating; Chemical vapor deposition (CVD) methods such as plasma CVD, thermal CVD, and laser CVD.

Among them, the plasma CVD method is preferable in view of the adhesion between the elastic layer and the surface layer (SiOx film), the treatment time and the treatment temperature, the simplicity of the device, and the uniformity of the surface layer obtained.

Hereinafter, an example of a method of forming a SiOx film by the plasma CVD method will be described.

3 is a schematic view of an apparatus for forming a SiOx film by the plasma CVD method.

The apparatus includes a vacuum chamber 41, a flat plate electrode 42 placed in parallel, a raw material gas cylinder and a raw material liquid tank 43, a raw material supply means 44, a gas exhaust means 45 in the chamber, a high frequency And a motor 47 for rotating the supply power source 46 and the elastic roller 48. [

By using the apparatus shown in Fig. 3, a developing roller having a SiOx film as its surface layer can be manufactured by the following procedures (1) to (4).

Procedure (1) An elastic roller 48 having an elastic layer formed on the shaft core between the flat plate electrodes 42 is provided, and the motor 47 is driven to rotate in the circumferential direction so that the resulting SiOx film becomes uniform.

Procedure (2) The inside of the vacuum chamber 41 is evacuated by the evacuation means.

(3) The raw material gas is introduced from the raw material gas inlet, the high frequency power is supplied to the flat plate electrode 42 by the high frequency power supply source 46, and plasma is generated to perform film formation.

(4) After the lapse of a predetermined time, the supply of the raw material gas and the high frequency power is stopped, and air or nitrogen is introduced (leaked) into the vacuum chamber 41, and the elastic roller 48 is taken out.

It is possible to manufacture a developing roller having a surface layer containing a SiOx film containing carbon by the above procedure. Further, the elastic roller 48 subjected to the plasma CVD treatment may be treated at the same time as long as it can be placed under a uniform plasma atmosphere.

Here, as the raw material gas, an organosilicon compound in a gaseous state or a gaseous state is introduced into the reactor, if necessary, in the presence or in the absence of a gas such as an inert gas or an oxidizing gas together with the hydrocarbon compound. Examples of the hydrocarbon compound include, for example, toluene, xylene, methane, ethane, propane, and acetylene.

Examples of the organic silicon compound include the following. Hexamethyldisiloxane, tetramethyldisiloxane, 1,1,3,3-tetramethyldisiloxane, hexamethyldisiloxane, vinyltrimethylsilane, methyltrimethoxysilane, hexamethyldisilane, methylsilane, dimethylsilane, trimethylsilane, tetramethylsilane, Propylsilane, phenylsilane, vinyltriethoxysilane, vinyltrimethoxysilane, tetramethoxysilane, tetraethoxysilane, phenyltrimethoxysilane, methyltriethoxysilane, octamethylcyclotetrasiloxane.

From the viewpoint of handling safety, 1,1,3,3-tetramethyldisiloxane, hexamethyldisiloxane and tetramethylsilane are preferable.

The silane source is not limited to the organic silicon compound, and silane, aminosilane, and silazane can also be used.

If the organic silicon compound or the like is in a gaseous state, it is used as it is, and if it is a liquid at room temperature, it is heated and vaporized and transported by an inert gas or by bubbling with an inert gas. Further, in the case of a solid at room temperature, it is heated and vaporized, and is transported by inert gas. Further, vaporization may be promoted while the raw material is in a reduced pressure state.

Further, when the raw material organic silicon compound is an oxygen-containing compound, it is possible to deposit a SiOx film even without oxygen. In addition to the raw material gas, or in addition to the raw material gas, an oxidizing gas such as oxygen (N ₂ O, CO _2, etc.) having oxygen and oxidizing power is introduced into the vacuum chamber. Examples of the inert gas usable in the above include helium, argon and nitrogen.

The presence ratio of the silicon atoms in the SiOx film, the oxygen atoms chemically bonded to the silicon atoms, and the carbon atoms chemically bonded to the silicon atoms can be controlled by the mixing ratio of the source gas to be introduced, the high-frequency power to be supplied, and the like Do.

Specifically, for example, the value of O / Si can be increased by increasing the ratio of the oxygen gas in the blending ratio of the above-described organic silicon compound and oxygen gas. The value of C / Si can be increased by lowering the ratio of oxygen gas.

Further, by increasing the high-frequency power, the values of O / Si and C / Si can be lowered. Further, by using the above hydrocarbon compounds in combination, the values of O / Si and C / Si can be increased according to the amount of the hydrocarbon compound used.

As a method for producing the SiOx film by the wet method, the following methods are exemplified.

A mixture of an inorganic polymer precursor solution (for example, a perhydro polysilazane solution or the like) and a polymer solution having a hydroxyl group (for example, 2-hydroxyethyl methacrylate or the like) is uniformly coated on the elastic layer, And then the coating film of the mixture is cured by heating or ultraviolet irradiation.

In the above method, the values of O / Si and C / Si can be controlled by changing the molar ratio of the solution of the inorganic polymer precursor and the solution of the polymer.

Here, the surface of the elastic layer may be subjected to activation treatment such as ultraviolet irradiation, electron beam irradiation, or plasma treatment so that the mixture can be applied well before the raw material mixture for SiOx film is applied on the elastic layer.

The thickness of the SiOx film thus formed is preferably 15 nm or more and 5000 nm or less, more preferably 300 nm or more and 3000 nm or less. By setting the film thickness within the above-mentioned numerical range, it is practically sufficient to abrade the film due to long-term use. Further, even when a film of SiOx is produced by the CVD method described above, it is possible to effectively inhibit the elastic layer from being excessively heated to change the characteristics of the elastic layer.

The film thickness of the formed SiOx film was measured by using a thin film thickness measuring apparatus (trade name: F20-EXR; manufactured by FILMETRICS Co., Ltd.) in three places at equal intervals from the end portion in the longitudinal direction of the developing roller, And the average value of the values obtained by measuring 9 places in total.

The developing roller in the present invention preferably has a current value measured when DC 50 V is applied by rotating the developing roller as shown in Fig. 4, preferably 5 to 5000 占,, more preferably 100 to 500 占Do. By setting the current value to the above-described numerical range, it is easy to obtain a developing bias sufficient for developing when the electrostatic latent image formed on the electrophotographic photosensitive drum is developed by the toner. As a result, an electrophotographic image of a sufficient concentration can be obtained. Furthermore, since a bias leak is unlikely to occur even when a pinhole is formed on the surface of the electrophotographic photosensitive drum, it is possible to effectively suppress occurrence of horizontal stripe or the like caused by the pinhole in the electrophotographic image.

A load of 500 g each is applied to the shaft-shaped body exposed portion of the developing roller 1 to the cylindrical electrode 51 made of SUS having a diameter of 40 mm and the outer circumferential surface of the developing roller 1 is brought into contact. In this state, the cylindrical electrode 51 is rotated, and the developing roller 1 is rotated in the circumferential direction at a speed of 24 rpm by the interlocking rotation. At a time when the rotation is stabilized, a voltage is applied to the shaft core from the direct current power source 52, and a voltage of 50 V is applied between the shaft and the cylindrical electrode. The environment at this time is set to 20 ° C and 50% RH. The current value is measured by the current meter 53 at that time for one week of the developing roller 1, and the average value thereof is determined as the current value. In the present specification, the current value thus measured is referred to as " current value of the developing roller ". It is important to control the current value of the developing roller uniformly while appropriately keeping the electric field intensity for moving the toner uniform and uniform.

The developing roller of the present invention is useful as a developing roller of an image forming apparatus such as a copying machine, a facsimile, and a printer, and as a developing roller of a process cartridge in an image forming apparatus of the process cartridge type.

Fig. 5 schematically shows an example of a color electrophotographic image forming apparatus equipped with the developing roller of the present invention. This will be described below with reference to FIG.

The color electrophotographic image forming apparatus shown in the schematic diagram of Fig. 5 has image forming sections 10 (10a to 10d) provided for each color toner of yellow Y, magenta M, cyan C and black BK in a tandem format. The specifications of the image forming section 10 are the same in basic configuration although they differ slightly depending on the toner characteristics of the respective colors. The image forming unit 10 is provided with a photosensitive drum 21 as a latent image bearing member that rotates in the direction of the arrow. There are provided a charging member 26 for uniformly charging the photosensitive drum 21, an exposure means for forming a latent electrostatic image by irradiating the uniformly charged photosensitive drum 21 with laser light 25, And a developing device 22 for supplying the toner to the formed photosensitive drum 21 to develop the electrostatic latent image. The bias power source 32 is applied to the toner image on the photosensitive drum 21 from the back side of the recording medium 36 such as paper that is fed by the feeding roller pair 37 and conveyed by the conveyance belt 34 There is provided a transfer member having a transfer roller 31 to be transferred onto the recording medium 36. [ The conveyance belt 34 is engaged with the drive roller 30, the driven roller 35 and the tension roller 33 so that the toner image formed in each image forming portion is successively superimposed on the recording medium 36, And is controlled so as to move in synchronism with the image forming section to convey the recording medium 36. [ The recording medium 36 is electrostatically adsorbed on the conveying belt 34 and conveyed by the action of the adsorption roller 38 provided immediately before the conveying belt 34 is folded.

The color electrophotographic image forming apparatus also includes a fixing device 29 for fixing the toner image superimposed and transferred on the recording medium 36 by heating or the like, and a conveying device (not shown) for discharging the image- ). The recording medium 36 is peeled from the conveying belt 34 by the action of the peeling device 39 and is sent to the fixing device 29. [

On the other hand, the image forming unit 10 is provided with a cleaning member having a cleaning blade 28 for removing the transfer residual toner remaining on the photosensitive drum 21 without being transferred, and a cleaning blade 28 for cleaning the surface, A waste toner container 27 for storing waste toner is provided. The cleaned photosensitive drum 21 is allowed to stand by for image formation.

It is also possible to form the process cartridge with the photosensitive drum 21, the charging member 26, the developing device 22, the cleaning blade 28 and the waste toner container 27 integrally.

The developing device 22 provided in the image forming section 10 is provided with a toner container 24 for containing the toner 23 and a developing device 22 provided at a portion exposed from the toner container to close the opening of the toner container, And a developing roller 1 facing the developing roller 1 are provided. The toner container 24 is provided with a roller-shaped toner applying member 7 that contacts the developing roller 1 and supplies the toner to the developing roller 1; And a toner amount regulating blade 9 for performing friction charging is provided. As the toner applying member 7, for example, a foamed sponge body or a polyurethane foam is provided on a shaft body, or a perforated structure in which fibers such as rayon or polyamide are put on the surface of the developing roller 1, It is preferable from the point of view of elimination. The toner applying member 7 is desirably disposed at an appropriate contact width with the developing roller 1 and is preferably rotated in the opposite direction with respect to the developing roller 1 at the contact portion thereof.

As described above, the process cartridge of the present invention is detachably mountable to the main assembly of the electrophotographic image forming apparatus and includes the developing roller. 6 is a schematic view of an example of a process cartridge for a monochromatic image forming apparatus.

The developing roller 1 is mounted in contact with the photosensitive drum 21 and the toner applying member 7. The toner 23 put in the toner container 24 can be supplied to the developing roller 1 by the toner applying member 7. At this time, the amount is adjusted by the toner amount regulation blade 9. On the other hand, an electrostatic latent image is formed on the photosensitive drum 21 charged by the charging member 26 by the laser beam 25. The electrostatic latent image is developed by the toner carried on the developing roller 1 Thereby forming a toner image. The toner image of the photosensitive drum 21 is transferred onto a recording medium such as paper. The toner remaining on the photosensitive drum 21 is scraped off by the cleaning blade 28 and dropped onto the waste toner container 27.

Hereinafter, the present invention will be described in more detail with reference to Examples, but the present invention is not limited thereto.

Unless otherwise specified, reagents used are those having a purity of 99.5% or more.

Production Example 1 (Production of elastic roller 1)

The following materials were blended to prepare a liquid silicone rubber base material.

- Dimethylpolysiloxane (vinyl group content 0.15% by mass) of both terminal vinyl groups: 100 parts by mass,

7 parts by mass of quartz powder (trade name: Min-USil; manufactured by Pennsylvania Glass Sand) as a filler and

Carbon black (trade name: Denka black, powder type; manufactured by Denki Kagaku Kogyo K.K.): 10 parts by mass.

0.5 mass parts of a complex of chloroplatinic acid and divinyltetramethyldisiloxane (0.5 mass%) as a curing catalyst was added to the base material to prepare solution A. Further, 1.5 parts by mass of a dimethylsiloxane-methylhydrogensiloxane copolymer having both terminal Si-H groups (H content of 0.30% bonded to Si atoms) was blended in the base material to prepare liquid B.

A cylindrical core body made of a SUM material having a diameter of 6 mm and a length of 250 mm, whose surface was primed, was disposed in the center of the cylindrical mold. The mold A was mixed with the solution A and the solution B in a mass ratio of 1: 1, and the mixture was heated and cured at 130 ° C for 20 minutes and then cured at 200 ° C for 4 hours. To obtain an elastic roller 1 having a layer.

Production Example 2 (Production of elastic roller 2)

The following materials were melted and kneaded using a twin screw extruder having a diameter of 30 mm and L / D 32 and extruded to prepare a resin mixture.

100 parts by mass of a polyolefin elastomer (trade name: Santoprene 8211-25; manufactured by AES Japan K.K.) and

占 MT Carbon Black (trade name: SUMAX FLOFOM N990; manufactured by CANCAB CO., LTD.): 40 parts by mass.

Subsequently, the resin mixture was pelletized. This pellet was formed into a resin layer on a shaft body (diameter 6 mm, length 250 mm) using a crosshead extruder. The end of the resin layer was cut, and the resin layer portion was polished with a rotary grinder to obtain an elastic roller 2 having an elastic layer with a thickness of 3 mm.

Production Example 3 (Production of elastic roller 3)

The same procedure as in Production Example 2 was carried out except that the polyolefin elastomer (Santoprene 8211-25; manufactured by AES Japan K.K.) was changed to an olefin elastomer (trade name: Santoprene 8211-45; manufactured by AES Japan K.K.) Thereby obtaining the elastic roller 3.

≪ Production Example 4 > (Production of elastic roller 4)

The procedure of Production Example 2 was repeated except that the polyolefin elastomer (trade name: Santoprene 8211-25; manufactured by AES Japan K.K.) was changed to LDPE (trade name: Novatec LD LJ902; manufactured by Nippon Polyethylene K.K.) Elastic roller 4 was obtained.

Production Example 5 (Production of elastic roller 5)

Except that the polyolefin elastomer (trade name: Santoprene 8211-25; manufactured by AES Japan K.K.) was changed to LDPE (trade name: Novatec LD LJ802; manufactured by Nippon Polyethylene K.K.) Roller 5 was obtained.

≪ Production Example 6 > (Production of elastic roller 6)

Except that a polyolefin elastomer (trade name: Santoprene 8211-25; manufactured by AES Japan K.K.) was changed to EVA (trade name: EVAPLEX EV45LX; manufactured by Mitsui-Dupont Polychemical Co., Ltd.) Thereby obtaining the elastic roller 6.

≪ Example 1 >

The elastic roller 1 was provided in the plasma CVD apparatus shown in Fig. Thereafter, the pressure in the vacuum chamber was reduced to 1 Pa by using a vacuum pump. Thereafter, a mixed gas of 1.0 sccm of steam of hexamethyldisiloxane as a raw material gas, 1.5 sccm of oxygen and 22.5 sccm of argon gas was introduced into the vacuum chamber, and the pressure in the vacuum chamber was set to 25.3 Pa. After the pressure was fixed, a power of 13.56 MHz and 120 W was supplied from the high frequency power source to the flat plate electrode, and a plasma was generated between the electrodes. The elastic roller 1 provided in the vacuum chamber was rotated at 24 rpm for 3 minutes. After the end of the processing, the power supply was stopped, the raw material gas remaining in the vacuum chamber was evacuated, and air was introduced into the vacuum chamber until it was atmospheric pressure. Thereafter, the developing roller having the surface layer formed thereon was taken out.

The surface of the obtained developing roller was found to be 1.56 and 0.32, respectively, when the abundance ratio O / Si and abundance ratio C / Si were determined by an X-ray photoelectron spectroscope.

Further, the film thickness of the surface layer of the developing roller was measured using a thin film thickness measuring apparatus (trade name: F20-EXR; manufactured by FILMETRICS), and the film thickness was 1530 nm. In addition, the measurement was carried out at three points in the longitudinal direction of the developing roller and at nine points in the total of three points in the circumferential direction, and the average value of the obtained values was taken as the film thickness.

Further, under the environment of a temperature of 20 캜 and a humidity of 50% RH, a current value of the developing roller measured while rotating at a speed of 24 rpm by applying a voltage of 50 V was 270..

The tensile modulus of elastic layer (hereinafter referred to as " elastic layer + surface layer ") having a surface layer measured using a test piece of a roller half of 100 mm in length produced from the developing roller along Fig. 2 was 1.0 MPa. The tensile modulus of elasticity was measured in five samples using a universal tensile tester (trade name: Tensilon RTC-1250A; manufactured by Orientech Co., Ltd.) in a measurement environment at a temperature of 20 ° C and a humidity of 60% RH, Respectively.

≪ Example 2 >

The elastic roller 2 was used and the time for the plasma CVD treatment in forming the surface layer was set to 4 minutes. A developing roller was produced in the same manner as in Example 1 except for the above.

Various characteristics of the obtained developing roller were analyzed in the same manner as in Example 1. [ The results are shown in Table 1.

≪ Example 3 >

A developing roller was obtained in the same manner as in Example 2 except that the time for the plasma CVD treatment was set to 10 seconds. Table 1 shows the results of the analysis of the developing roller.

<Example 4>

A developing roller was obtained in the same manner as in Example 2 except that the time for the plasma CVD treatment was changed to 8 seconds. Table 1 shows the results of the analysis of the developing roller.

&Lt; Example 5 >

A developing roller was obtained in the same manner as in Example 2 except that the time for the plasma CVD treatment was changed to 10 minutes. Table 1 shows the results of the analysis of the developing roller.

&Lt; Example 6 >

A developing roller was obtained in the same manner as in Example 2 except that the time for the plasma CVD treatment was changed to 11 minutes. Table 1 shows the results of the analysis of the developing roller.

&Lt; Example 7 >

In the formation of the surface layer, the composition of the raw material gas was 1.0sccm of hexamethyldisiloxane vapor, 2.5sccm of oxygen and 21.5sccm of argon gas. The time for the plasma CVD treatment was 30 seconds. A developing roller was obtained in the same manner as in Example 2 except for the above. Table 1 shows the results of the analysis of the developing roller.

&Lt; Example 8 >

In the formation of the surface layer, the composition of the raw material gas was 1.0 sccm of hexamethyldisiloxane vapor, 0.5 sccm of oxygen and 23.5 sccm of argon gas. The time for the plasma CVD treatment was 6 minutes. A developing roller was obtained in the same manner as in Example 2 except for the above. Table 1 shows the results of the analysis of the developing roller.

&Lt; Example 9 >

A developing roller was obtained in the same manner as in Example 8 except that the time for the plasma CVD treatment was changed to 3 minutes in the formation of the surface layer. Table 1 shows the results of the analysis of the developing roller.

&Lt; Example 10 >

A developing roller was obtained in the same manner as in Example 8 except that the time for the plasma CVD treatment was changed to 1 minute in the formation of the surface layer. Table 1 shows the results of the analysis of the developing roller.

&Lt; Example 11 >

A developing roller was obtained in the same manner as in Example 2 except that the elastic roller 3 was used. Table 1 shows the results of the analysis of the developing roller.

&Lt; Example 12 >

A developing roller was obtained in the same manner as in Example 2 except that the elastic roller 4 was used. Table 1 shows the results of the analysis of the developing roller.

&Lt; Example 13 >

A developing roller was obtained in the same manner as in Example 1 except that the elastic roller 5 was used. Table 1 shows the results of the analysis of the developing roller.

&Lt; Example 14 >

A developing roller was obtained in the same manner as in Example 1 except that the elastic roller 6 was used. Table 1 shows the results of the analysis of the developing roller.

&Lt; Example 15 >

The conditions for forming the surface layer in Example 2 were as follows: raw material gas composition 1, 1, 3, 3-tetramethyldisiloxane steam 1.0 sccm, oxygen 2.5 sccm and argon gas 22.5 sccm, chamber pressure 50.6 Pa and high frequency power 13.56 MHz , And 200W respectively. The time for the plasma CVD treatment was 1 minute. A developing roller was obtained in the same manner as in Example 2 except for the above. Table 1 shows the results of the analysis of the developing roller.

&Lt; Example 16 >

The raw material gas composition was changed to tetramethylsilane vapor of 1.0 sccm, oxygen of 0.5 sccm, and argon gas of 22.5 sccm, and the time of the plasma CVD treatment was set to 10 minutes. A developing roller was obtained in the same manner as in Example 2 except for the above. Table 1 shows the results of the analysis of the developing roller.

&Lt; Example 17 >

The surface of the elastic layer of the elastic roller 2 was surface-treated with excimer light. Subsequently, a mixed solution of 250 g of a perhydro polysilazane solution (trade name: Aquamika NP110-5; AZ Electronic Materials Co., Ltd.) and 3 g of 2-hydroxyethyl methacrylate was coated by a dipping method. Thereafter, a developing roller having a surface layer formed by air drying for one day was obtained. Table 1 shows the results of the analysis of the developing roller.

&Lt; Example 18 >

A developing roller was obtained in the same manner as in Example 1 except that the surface treatment time was changed to 6 minutes in the formation of the surface layer. Table 1 shows the results of the analysis of the developing roller.

&Lt; Example 19 >

A developing roller was obtained in the same manner as in Example 1, except that the composition of the raw material gas was changed to 1.0 sccm of hexamethyldisiloxane vapor and 21.5 sccm of argon gas in the formation of the surface layer, and the duration of the plasma CVD treatment was changed to 3 minutes. Table 1 shows the results of the analysis of the developing roller.

&Lt; Example 20 >

In forming the surface layer of Example 1, 20 sccm of hexamethyldisiloxane vapor was introduced into the vacuum chamber as the raw material gas composition, and the pressure in the vacuum chamber was set to 6 Pa. Further, 150 W of electric power was supplied to the parallel plate electrodes by a high frequency power source and treated for 5 minutes. A developing roller was obtained in the same manner as in Example 1 except for the above. Table 1 shows the results of the analysis of the developing roller.

&Lt; Example 21 >

In forming the surface layer of Example 20, a mixed gas of 10 sccm of hexamethyldisiloxane vapor and 10 sccm of toluene vapor was introduced as a raw material gas into the vacuum chamber, and the pressure in the vacuum chamber was set to 6 Pa. A developing roller was obtained in the same manner as in Example 20 except for the above. Table 1 shows the results of the analysis of the developing roller.

&Lt; Example 22 >

In forming the surface layer of Example 21, 3sccm of vapor of hexamethylsiloxane as a raw material gas was introduced into the vacuum chamber, and the pressure in the vacuum chamber was set to 2Pa. In addition, 200 W of power was supplied to the parallel plate electrode by the high frequency power source. A developing roller was obtained in the same manner as in Example 21 except for the above. Table 1 shows the results of the analysis of the developing roller.

&Lt; Example 23 >

In forming the surface layer of Example 22, a mixed gas of 10 sccm of hexamethyldisiloxane vapor and 20 sccm of toluene vapor was introduced as a raw material gas into the vacuum chamber, and the pressure in the vacuum chamber was set to 8 Pa. In addition, 30 W of power was supplied to the parallel plate electrodes by the high frequency power source. A developing roller was obtained in the same manner as in Example 22 except for the above. Table 1 shows the results of the analysis of the developing roller.

&Lt; Comparative Example 1 &

In forming the surface layer of Example 1, the composition of the raw material gas was changed to 1.0 sccm of tetramethylsilane vapor, 2.5 sccm of oxygen and 21.5 sccm of argon gas. The time for the plasma CVD treatment was 2 minutes. A developing roller was obtained in the same manner as in Example 1 except for the above. Table 1 shows the results of the analysis of the developing roller.

&Lt; Comparative Example 2 &

In forming the surface layer of Example 20, 30 sccm of vapor of hexamethyldisiloxane was introduced as a raw material gas into the vacuum chamber, and the pressure in the vacuum chamber was set to 6 Pa. Further, 200 W of power was supplied by the high frequency power source. A developing roller was obtained in the same manner as in Example 20 except for the above. Table 1 shows the results of the analysis of the developing roller.

&Lt; Comparative Example 3 &

A mixed solution containing methyl ethyl ketone as a main solvent adjusted to a concentration of 5% in terms of solid content was prepared as a heat curing type silicone adhesive sealant (trade name: TSE3251-C, manufactured by Momentive Performance Materials). To this mixed solution, 21 parts by weight of carbon black (trade name: Denka black; manufactured by Denki Kagaku Kogyo K.K., powder type) was added to the resin component and sufficiently stirred to prepare a coating solution for surface layer formation.

The elastic roller 1 having the surface of the elastic layer surface-treated with excimer light was immersed in the coating solution, pulled up and dried, and further heated at 140 캜 for 2 hours to obtain a developing roller. Table 1 shows the results of the analysis of the developing roller.

(Evaluation 1)

The developing rollers obtained in the above Examples and Comparative Examples were evaluated as follows. The evaluation results are shown in Table 2.

The laser printer (trade name: Laser shot LBP-1310, manufactured by Canon Inc.) used for evaluation was a machine for longitudinal printing on A4 paper, and the output speed of the recording medium was 16 ppm and the resolution of the image was 1200 dpi. The contact pressure and entry amount of the developing roller to the toner amount regulating blade were such that the amount of toner carried on the developing roller was 0.35 mg / cm ² .

(1) evaluation of the presence and degree of image defects resulting from cracking of the surface layer;

Each of the developing rollers according to each of the Examples and Comparative Examples was inserted as a developing roller into a cartridge of an electrophotographic laser printer (trade name: Laser Shot LBP-1310, manufactured by Canon Inc.). The cartridge was loaded in the electrophotographic laser printer, and an electrophotographic image was output in an environment of a temperature of 25 캜 and a humidity of 50% RH. More specifically, 10,000 prints of 1% of the print data were printed using black toner, and solid black images and halftone images were output one by one in order. The halftone image had a density of 0.7 as measured by a densitometer (trade name: Macbeth Color Checker RD-1255; manufactured by Macbeth Co.). For the solid black image and the halftone image, image defects resulting from cracks in the surface layer were evaluated based on the following criteria.

&Quot; None &quot;: occurrence of streaks due to cracks in the surface layer of the developing roller is not observed in the image

&Quot; Minor &quot;: Streaks caused by cracks in the surface layer of the developing roller are recognized in the image, but there is no practical problem

"Yes": Streaks due to cracks in the surface layer of the developing roller were confirmed in the image

(2) film formation;

The surface of the developing roller after the output of the image used in the evaluation of the above (1) was observed with a microscope (trade name: Digital Microscope VH-8000; manufactured by Giance). The presence or absence of film formation and the presence or absence of image defects resulting from film formation in the image used in the evaluation of the above (1) were evaluated according to the following criteria.

"A": No filming on the developing roller

&Quot; B &quot;: Although toner filming occurs slightly on the developing roller, image defects due to the film formation are not confirmed in the evaluation image

&Quot; C &quot;: filming of the toner on the developing roller occurs, and image defects due to the filming are confirmed in the evaluation image

(3) permeation;

The effect of inhibiting the penetration of low molecular weight substances from the elastic layer of the developing roller by the surface layer according to the present invention was tested as follows.

A new developing roller according to each of the examples and comparative examples was inserted into the process cartridge and left in contact with the toner amount regulating blade and the photosensitive drum for 30 days under conditions of 40 DEG C and 95% RH. Thereafter, the process cartridge after being left standing was inserted into a laser printer, and a solid black image and a halftone image were outputted. The image was observed with naked eyes, and the presence or absence of a problem with the electrophotographic image caused by adhesion of the exudation from the elastic layer to the photosensitive drum and its degree were evaluated based on the following criteria.

"None": There is no problem of image due to sticking out

"Minor": The problem of the image due to the sticking of the exudation is slightly confirmed, but there is no practical problem

"Yes": Problems of burning due to adhesion of seeping were observed

As shown in Table 2, from the results of evaluation item (1), it was found that the developing roller according to the present invention had sufficient flexibility. From the results of evaluation item (2), it was found that the developing roller according to the present invention had a surface with excellent toner releasability. From the results of evaluation item (3), it was found that the developing roller according to the present invention can effectively inhibit permeation of low molecular weight components from the elastic layer.

(Evaluation 2)

Next, the developing rollers of Examples 1 to 23 were evaluated for the following evaluation items (4) to (9).

(4) cloudiness;

The solid white image output in the evaluation item (1) was measured for the reflection density with a photovoltaic reflection densitometer (trade name: TC-6DS / A; manufactured by Tokyo Denshoku Co., Ltd.) (%), And evaluated according to the following criteria.

A: less than 1.5%

B: 1.5% or more and less than 3.0%

C: 3.0% or more

(5) image density;

The solid black image output in the evaluation item (1) was measured using a densitometer (trade name: Macbeth Color Checker RD-1255; manufactured by Macbeth Co.) and evaluated according to the following criteria.

A: All 1.3 to less than 1.6

B: One side is less than 1.3 and less than 1.6, the other side is less than 1.3 or more than 1.6

C: all less than 1.3 or 1.6 or more

(6) concentration unevenness;

For the solid black image and the halftone image output in the evaluation item (1), density unevenness was visually observed and evaluated based on the following criteria. In addition, density unevenness is generally the most visible in a halftone image, and is relatively easy to be revealed in a solid black image.

A: No image was confirmed by naked eyes,

B: Unevenness in density was confirmed in the halftone image, and unevenness in density was not confirmed in the solid black image

C: Unevenness in density is confirmed in any image

(7) Leak image;

With respect to the solid black image and the halftone image outputted in the evaluation item (1), the presence or absence of the occurrence of the horizontal stripe in the period of the photosensitive drum was visually confirmed. Then, evaluation was made according to the following criteria.

"None": Horizontal stripes are not observed

"Minor": slight occurrence of horizontal stripe is confirmed but there is no practical problem

"Yes": occurrence of horizontal stripe is confirmed

(8) durability;

The surface of the developing roller after the output of the image used for the evaluation of the evaluation item (1) was observed with a digital microscope (trade name: VH-8000; manufactured by Kabushiki Kaisha Genseng Co., Ltd.), and the presence / And evaluated according to the following criteria.

"None": Peeling of the surface layer is not confirmed

"Minor": slight peeling of surface layer confirmed

"Yes": Peeling of surface layer confirmed

(9) set property;

The setting property of the developing roller in contact with the toner amount regulation blade was tested as follows.

A new developing roller according to each example was inserted into the process cartridge and left in contact with the toner amount regulating blade for 30 days under the environment of 40 DEG C and 95% RH. Thereafter, the process cartridge after being left standing was inserted into a laser printer, and a solid black image and a halftone image were outputted. The image was observed with naked eyes, and the presence or absence of the occurrence of the horizontal stripe caused by the toner amount regulating blade contact marks and the degree thereof were evaluated based on the following criteria.

"None": Horizontal stripes based on contact marks are not confirmed

"Minor": Horizontal stripes based on contact marks are slightly visible, but there are no practical problems

"In": Horizontal stripes based on contact trace are identified

Table 3 shows the results of the evaluation items (4) to (9).

This application claims priority from Japanese Patent Application No. 2007-118781, filed on April 27, 2007, the contents of which are incorporated herein by reference.

Claims (8)

A developing roller for supporting and conveying a toner and developing the electrostatic latent image of the photosensitive drum with toner, Wherein the developing roller has an axial core, an elastic layer and a surface layer in this order, Wherein the surface layer comprises a silicon oxide film containing a carbon atom chemically bonded to a silicon atom, wherein the silicon oxide film has an abundance ratio (O / Si) of an oxygen atom forming a chemical bond with a silicon atom to a silicon atom is 0.65 or more and 1.95 or less, and the abundance ratio (C / Si) of the carbon atoms forming the chemical bond with the silicon atom to the silicon atom is 0.05 or more and 1.65 or less. The developing roller according to claim 1, wherein the surface layer has a thickness of 15 nm to 5000 nm. The developing roller according to claim 2, wherein the surface layer has a thickness of 300 nm or more and 3000 nm or less. The developing roller according to claim 1, wherein the elastic layer having the surface layer on the upper side has a tensile modulus of 1.0 MPa or more and 100.0 MPa or less. The developing roller according to claim 1, wherein a current value measured when a voltage of 50 V is applied to the rotating developing roller is 5 A to 5000 A inclusive. The developing roller according to claim 1, wherein the surface layer covers the surface of the elastic layer, and the surface layer includes the silicon oxide film. An electrophotographic process cartridge detachably mounted on an electrophotographic image forming apparatus main body, Wherein the developing roller assembled in said cartridge is the developing roller according to claim 1. An electrophotographic image forming apparatus having a photosensitive drum and a developing roller disposed in contact with the photosensitive drum, Wherein the developing roller is the developing roller according to any one of claims 1 to 7. An electrophotographic image forming apparatus comprising:

Images